Thermostatic



Patented Feb. 25, 1947 UNI-TED STATES PATENT OFFICE V 2,416,468 f THEEMOSTATIC DAMPER.

William H. Carsten, Seattle, Wash.

Application January 18, 1944,-Serial No. 518371 5 I (c1. zoo-9a.)

4 Claims.

This invention relates to automatic-dampers. and it has reference more particularlyto dampers designed especially for installation in the stack connections of domestic furnaces using the presentday types of oil burners as the heat supplying units; it being the principal object of the invention to provide a damper mechanism including a damper plate that is disposed in the stack connection and with which a thermostatic element is associated to automatically adjust the plate'from an open position to a closed position upon a certain predetermined degree of heat being reached, thus to conserve heat by preventing its wasting by flow up the stack.

Explanatory to the invention, it will here be mentioned, in brief, that when an oil burner of any of those types now used in domestic heating plates or furnaces, is first set into operation in a cold furnace, it is necessary for'insuri'ng complete combustion offuel, that there be a goOd draft through the combustion chamber and to the stack. However, after the cold furnace has been brought up to satisfactory operating heat, it is desirable from the standpoint of fuel economy that the stack connection be restricted against the strong updraft, thus to prevent a great percentage of the heat from escaping up the chimney. l

Furthermore, it maybe said that while it is desirable from a safety standpoint, on starting up a cold .furnace, to keep the stack damper or draft open, itcan, with safety, be closed after the furnace is up to normal working temperature.

In 'view of the foregoing, it has been the main object of this invention to provide an automatic damper mechanism that may be applied'to a stack connection'between a furnace combustionchamber and chimneythat will operate under control of temperature of gasesflowing to thechimney, to close the passage in the stack connection against unrestricted outfiowof the hotgases just as soon as this can be done with safety.

It is also an object of the'invention to provide a damper mechanism of an automatic character to be applied to the stack connection in "such manner as to provide for a controlled by-passing of gases past the damper to thestack while th damper is in closed position.

Still further objects of the invention reside .in the provision of auxiliary damper means forregulating the lay-passing of gases past the closed damper to best suit any particular draft condition of the stack connection inlwhich the damper may be placed. Still further objects of the invention aeside in 2 the details of construction and combination of parts aswill hereinafter be fully described.

In accomplishing these and other objects of the invention,I have provided the improved details of construction, the preferred forms of which are illustrated in theaccompanying drawings, wherein- Fig. "1 is .an elevation, showing a part of a furnace and its stack connectionto which a damper mechanism embodied by the present invention has'been applied; a part of the stack being broken away for better showing of the damper plate.

Fig. 2 is an enlarged, sectional detail of a por tion of the stack connection, illustrating the ap-' plication of the damper mechanism thereto, and

showing the damper plate in its "fully closed position.

Fig. 3 'is a horizontal section through the I damper -mechanism on the line 3-3- in Fig. 2, showing the auxiliary damper plate and its adjusting means.

Fig. 4 is a vertical cross section on line l4 in'Fig.2.

Referring more in detail to the drawingsl designates a portion of a furnace which may be any one of "the ordinary types used for domestic heating purposes, having a stack connection 2 leading from the furnace fire boxer combustion chamber, to astack or chimney such as has been indicated at 3. In that'horizontal portion .of the stack connection, here designatedby' numeral 2a, a damper mechanism, embodying the present invention, has been applied. g 1

It will be understood that in the normal opera-' tion of a furnace, there will be a draft of hot gases and air flowing from the furnace to the stack as indicated by the arrows in Fig. 1. Furthermore, the strength of this draft depends upon certain variable conditions that results in quite a variation in the degree of draft in diffe-rentfurnaces, and itis for this reason that the auxiliary damper plate has been incorporated in the present device; This presently will be more fully explained.

Referring more particularly to Fig. 2, which shows a part of the stack connection 2 and damper mechanism in vertical section on the central longitudinal line of the connecting pipe, it is to beobserved that there is'a rectangular opening 5 of substantial proportions, formed in the top wall of the pipe 2, over which a-closed, damper supporting housing 6 is applied. The housing is of an inverted dish-like form and is formed with a flange "I about its periphery that is shapedto conform to the curva'ture of the-stack connection justing shaft H. I 1 extends rotatablythrough an opening I 2 in the top wall 60: of the housing, and at its upper end I along the end and side edges of the opening 5, as

. will be understood by reference to Figs. 2 and 3,

1 and this. flange is secured in a close, gas-tight j joint to the pipe by a pluralit of screw bolts 8 extended through the pipe wall and flange. Referring to the device as shown in Fig. 2, it will be understood that the housing 6 has a flat top wall 6w outset substantially from the pipe opening-and, thus the housing serves as a by-pass chamber whereby outflowing gases will be bypassed from one side of the damper to the other when the damper is closed, as will be understood i by reference to the line of arrows in Fig. 2,

Fixed in the housing and extending horizontally and transversely thereacross close to the opening 5, as shown in Fig. 3, is a bar l0, and extending vertically and rotatably through a hole V i in the bar is a damper plate supporting and ad- The upper end of the'shaft II is equipped with a knob i3.

' Fixed to the looser end portionof the'shaft H,

which extends to the center line of pipe 2, is a circular damper plate is. As shown in Fig. 3, the damper plate is horizontally divided along the joint l5 shown in Fig. 4, and it comprises an upper segmental portion i6, which is fixed rigidly to the shaft Ii and a relatively large lower portion ll which is hingedly suspended from the upper portion. The hinge connections here shown com ;prise wire loops l9 passed through perforations in the adjacent edges of the parts It and ll. 1 The lower portion may swing from the full line position in which it is shown in Fig. 2, toward and beyond the dotted line .positionpthat is; it may swing outwardly or to open position in the direction of flow of gases in the pipe 2.

Fixed within the housing 6 is a thermostatic bi-metal strip -inthe form of a helical coil which at one end is fixed to'a post 261depending from the housing top wall, and at its other end ;is fixed to the shaft II; this bi-metal strip opera Eating underthe influence of temperature changes ito rotate the shaft. the shaft ii inopposite'directions isdetermined by lugs Hand 28 onv the top wall, againstwhich stops a'projecting lug 29 on the knob l3 willengage. The lugs 2-"! and 28 are soplaced as to per- .lmit the damper platerto beturned through an angle of 90, thus to move from its closed posie Ition to its open position. I V

. With the device applied to the stack as shown in Fig. 1, it will be understood that when the The extent of rotation of damper is in open position, as it is there shown, gases flowing to the stack will pass in the direction indicated by the arrows and will go directly past the damper plate. Some gases, however, will flow through the housing 6, thus coming in direct contact with the bi-metal'strip 25. 'When the heat of the flowing gases acts on the bi-metal strip to ,raise its temperature sufiiciently, it will effectrotation of the damper control shaft. II,

and turn the damper plate to closed position, in i which it has been shown'in full lines in Fig; 2. When in fully closed position, the lug or extenjsion' 29 on the knob l3 contacts with the stop 28 to limit it against further turning; Thus, so long as theheat is maintained in the furnace, the damper. will be retained in this closed position. However, when heat is discontinued, the I bimetal strip will cool, and will operate to gradually adjust the damper plate to its open position, so that when the fire is again started, there will be no restriction to the draft and the necessary flow of air to insure against explosions and to give complete combustion will be provided.

Referring now more particularly to Figs. 2 and 4, it is noted that there is. an auxiliary, slide damper provided within the housing 6 to regposition. This'damper 35 is in the form of a flat plate which rests flatly upon the cross bar Ill between the side walls of the housing. At one end, the plate has an upturned flange 36 to which the inner endof an adjustingscrew 31 is rotatably fixed. The screw is threaded through an end wall of the housing and at its outer end has a head to which a screw driver may be applied to turn the screw thus to adjust the damper plate. This plate 35, forming the auxiliary damper, is usedto regulate the area of the passage between the bar In and the end wall of the housing at one side of the damper I4 so that the by-passing suit the particular furnace to which. the. automatic damper device is to be'applied. This ad'- justment of the plate 35 is made after installa tion of the damper device, and one or moretrial uses, so that the closing of the damper'M may be 'efiected at any desired stack, temperature or after any definite predetermined time interval. The hinging of the lower portion of the damper M insures that there can be a rapid escaping of gas in the event of an explosion taking place in the furnace, and in such case, the damper will swing to the open position indicated in dotted lines in Fig. 2.

If ,the dampermechanism is tobe used in a vertical stack connection,then the'end of rod I i that is extended below the fixed section of the damper plate, operates. to support the hinged bustion chamber and a stack, having a side wall opening of substantial length therein, a housing fitted'to the outside of the pipe and overlying the said side wall opening and having a chamber therein that'is open to the pipe through the said. wall opening, a rod rotatably mounted in the housing and extended centrally through thepipe wall openin and into, thepipe in a diametric direction, a damper plate fixed to the rod in the pipe passage and adapted to be moved by rotative adjustment of the rod between open and closed positions in the pipe, a thermostatic element lo cated in the housing chamber and operatively connectedwith the rod for its actuatiomand operable incident toa change of temperature in the I housing from a, cold furnace to a hot furnace 6 condition to movethe damper plate fromopen position, at which gases are permitted to flow freely through the pipe, to a closed position, at

which it diverts the pipe gases through the house ing chamber, and an auxiliary damper in the housing manually adjustable to more or less restrict the flow of gases through the chamber..

2. A device as recited in claim 1, wherein the auxiliary damper comprises a slidably adjustable plate. 7 33' I L 3. A device as recited in claim 1 wherein the ulate the flow of gases passing through the hous- I ing over the damper plate when it is in closed of gases may be more or less restricted to best 1. A pipe connection between a furnace com REFERENCES CITED The following references are of record in the file of this patent:

Number UNITED STATES PATENTS Name Date Parsons Mar. 18, 1932 Jacobs Feb. 21, 1928 Waltenberg Aug. 13, 1935 McWilliams Mar. 31, 1936 Mulce et a1. May 13, 1941 Anderson Dec. 10, 1940 Anderson Dec. 21, 1937 Barnes Jan. 26, 1943 McCollum Sept. 18, 1945 

